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[CodeGen] Don't re-sign null member function pointers #4131

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Merged
merged 1 commit into from
Mar 29, 2022
Merged

[CodeGen] Don't re-sign null member function pointers #4131

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15 changes: 10 additions & 5 deletions clang/lib/CodeGen/ItaniumCXXABI.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1070,11 +1070,16 @@ ItaniumCXXABI::EmitMemberPointerConversion(const CastExpr *E,
QualType srcType = E->getSubExpr()->getType();
const auto &curAuthInfo = CGM.getMemberFunctionPointerAuthInfo(srcType);
llvm::Constant *memFnPtr = llvm::ConstantExpr::getExtractValue(src, 0);
llvm::Constant *constPtr =
pointerAuthResignConstant(cast<llvm::User>(memFnPtr)->getOperand(0),
curAuthInfo, newAuthInfo, CGM);
constPtr = llvm::ConstantExpr::getPtrToInt(constPtr, memFnPtr->getType());
src = llvm::ConstantExpr::getInsertValue(src, constPtr, 0);
if (memFnPtr->getNumOperands() == 0) {
// src must be a pair of null pointers.
assert(isa<llvm::ConstantInt>(memFnPtr) && "constant int expected");
} else {
llvm::Constant *constPtr = pointerAuthResignConstant(
memFnPtr->getOperand(0), curAuthInfo, newAuthInfo, CGM);
constPtr =
llvm::ConstantExpr::getPtrToInt(constPtr, memFnPtr->getType());
src = llvm::ConstantExpr::getInsertValue(src, constPtr, 0);
}
}

// Under Itanium, reinterprets don't require any additional processing.
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8 changes: 8 additions & 0 deletions clang/test/CodeGenCXX/ptrauth-member-function-pointer.cpp
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Expand Up @@ -386,3 +386,11 @@ void test_builtin_ptrauth_type_discriminator() {
MethodTy1 gmethod0 = reinterpret_cast<MethodTy1>(&Base0::nonvirtual0);
MethodTy0 gmethod1 = reinterpret_cast<MethodTy0>(&Derived0::nonvirtual5);
MethodTy0 gmethod2 = reinterpret_cast<MethodTy0>(&Derived0::virtual1);

// CHECK: define void @_Z15testConvertNullv(
// CHECK: %[[T:.*]] = alloca { i64, i64 },
// store { i64, i64 } zeroinitializer, { i64, i64 }* %[[T]],

void testConvertNull() {
VariadicMethodTy0 t = (VariadicMethodTy0)(MethodTy0{});
}